1. Field of the Invention
The present invention relates to the use of compounds of Formula I for enhancing a sweet taste, masking an unpleasant taste by creating a sweet taste, and related uses. The invention is also directed to, among other things, compositions comprising a compound of Formula I that can be used in pharmaceutical, food, and other products as a sweetener enhancer or as a taste masking agent. In certain aspects, the invention provides methods and compositions for enabling one to prepare consumable products, such as food and pharmaceutical products, which retain a desired sweetness but contain lower amounts of sweetener, such as sugar, and in some cases fewer calories.
2. Background Art
Taste perception plays a critical role in the nutritional status and survival of both lower and higher animals (Margolskee, R. F., J. Biol. Chem. 277:1-4 (2002); Avenet, P. and Lindemann, B., J. Membrane Biol. 112:1-8 (1989)). The ability to taste has significance beyond providing people with pleasurable culinary experiences. For example, the ability to taste allows us to identify tainted or spoiled foods, and provides satisfying responses that may be proportionate to caloric or nutritive value.
There are generally considered to be only four or five categories of basic taste: sweet, sour, bitter, acid, and “umami” (the Japanese word describing the taste of monosodium glutamate; Hemess, M. S. & Gilbertson, T. A., 1999, Annu. Rev. Physiol. 61:873-900). These can be sub-classified as the appetitive tastes, such as salty, sweet and umami, which are associated with nutrient-containing foods, and the bitter and sour tastes elicited by toxic compounds.
The anatomic basis for the initial events of taste is the taste receptor cell (“TRC”), located in clusters referred to as “taste buds” (Lindemann, supra). Taste buds are distributed throughout the oral cavity, including the tongue as well as extra-lingual locations (see Hemess and Gilbertson). In the human tongue, taste buds are organized into three specialized types of specialized structures, namely fungiform, foliate, and circumvallate papillae. Each taste bud comprises between about 50 and 100 individual cells grouped into a cluster that is between 20 and 40 microns in diameter. Nerve fibers enter from the base of the taste bud and synapse onto some of the taste receptor cells. Typically, a single TRC contacts several sensory nerve fibers, and each sensory fiber innervates several TRCs in the same taste bud (Lindemann, supra).
When a subject ingests a tastant, and that tastant encounters a taste receptor cell in the appropriate concentration, an action potential is produced which, via synapses with primary sensory neurons, communicates the signal registered by the receptor, via afferent nerves, to the appropriate region of the sensory cortex of the brain, resulting in the perception of a particular taste by the subject.
Although taste perception is a vital function, sometimes it is useful to modify certain tastes. For example, many active pharmaceutical ingredients of medicines produce undesirable tastes, such as a bitter taste. Masking the bitter taste produced by the medicine by adding a sweetener enhancer may lead to improved acceptance by the patient.
Traditionally, sweeteners and flavorants have been used to mask the bitter taste of pharmaceuticals. The sweetener or flavorant is known to activate other taste pathways and at sufficiently high concentration this serves to mask the bitter taste of the pharmaceutical. Using large concentrations of sweeteners such as table sugar (sucrose) is undesirable because of the high number of calories and because it cannot be administered to diabetics. Artificial sweeteners such as aspartame and saccharin do not have these drawbacks but can have an undesirable aftertaste or present safety concerns if used in large quantities.
A number of other methods have been suggested to inhibit, alter, or mask unwanted tastes. However, the presently available compounds are lacking in desirable characteristics.
Another area in which enhancing sweet taste would be useful is in encouraging food intake in subjects who have an impaired ability to taste or in patients who have lost their appetites. Studies have shown increased food intake as palatability increased. Sorensen, et al., Int. J. Obes. Relat. Metab. Disord. 27(10):1152-66 (2003). For instance, certain drugs, such as antihypertensives and antihyperlipidemics, have been reported to produce untoward alterations in taste and may result in decreased food intake. Doty, et al., J. Hypertens. 21(10):1805-13 (2003). Taste impairment has also been associated with radiation treatments for head and neck cancer and this taste impairment has been considered to be one of the factors associated with reduces appetite and altered patterns of food intake. Vissink, et al., Crit. Rev. Oral Biol. Med. 14(3):213-25 (2003). Decreased food consumption has also been correlated with loss of taste sensations in the elderly. Shiffman, S. S., J. Am. Med. Ass'n 278(16):1357-1362 (1997). Enhancing the sweet taste of food could lead to increased consumption of foods containing these enhancers.
Therefore, there exists a need for compounds that can effectively enhance a sweet taste, preferably without exhibiting one or more of the limitations of the prior art sweetening agents.